Oxidation catalyst composition of unsaturated carboxylic acid

ABSTRACT

An oxidation catalyst represented by the following empirical formula

United States Patent 1 1 1111 3,882,047

Niina et al. Ma 6 1975 [54] OXIDATION CATALYST COMPOSITION OF 3,288,721 11/1966 Kerr 252/435 UNSATURATED CARBOXYLC ACID 3,342,849 9/1967 Brill et alm, 252/437 X D 3,385,796 5/1968 Kerr 1. 252 437 [75] Inventors: Akrlnko Nnna; Klyomorl Q 3,417,144 12/1968 Cahoy et al 252 437 x Kuniyoshi Tashiro, all Of Takaoka, 3,666,804 5/1972 Parthasarathy et al. 260/530 N Japan v Primary Examiner-Patrick P. Garvin [73] Asslgnee Eggs Zeon Tokyo Attorney, Agent, or FirmSherman & Shalloway [22] Filed: Aug. 27, 1973 [57] ABSTRACT [21] App], No 391,668 An oxidation catalyst represented by the following If 1 Related US. Application Data empmca Ormu a [62] Division of Ser No. 309,962, Nov. 28, 1972, Pat. No.

3,795,703 wherein Q is at least one element selected from the group consisting of T1, Rb, Cs and K; and R is at least [30] Foreign Application Priority Data one element selected from the group consisting of Cr, Nov. 30, 1971 Japan 1. 46-95949 3i, M and Ti; and b, C, d and 8 each represent the number of atoms of each element; the atomic ratio 521 [LS CL 252 435; 252 437; 2 0 530 N of azbzczd is 1:1-0.0l:l-0.01:20.0l;and e is the num- 51 int. 131 B0lj 11/82 ber of Oxygen atoms determined by the valence [58] Field of Search 260/530 N; 252/435, 437 quiremems 0f the other elements P The lysts can be used in the preparation of an unsaturated 5 Reterences Cited carboxylic acid which comprises reacting an unsatu- UNITED STATES PATENTS rated aldehyde with molecular oxygen at an elevated temperature in the vapor phase 3,156,706 11/1964 Kerr 252/435 X 3,254,110 5/1966 Sennewald et al... 252/437 x 4 Chums, N0 Drawings OXIDATION CATALYST COMPOSITION OF UNSATURATED CARBOXYLIC ACID This application is a division of U.S. application Ser. No. 309,962, filed November 28, 1972, now U.S. Pat. No. 3,795,703.

This invention relates to oxidation catalysts and more particularly to oxidation catalysts which, inter alia, can be used in a process for preparing unsaturated carboxylic acids by the vapor phase oxidation of unsaturated aldehydes.

Prior patents and literature relating to the vapor phase catalytic oxidation of unsaturated aldehydes are directed chiefly to the production of acrylic acid from acrolein, and very few relate to the production of methacrylic acid from methacrolein.

Oxidation of methacrolein using the catalysts heretofore found effective in the oxidation of acrolein results, in almost all cases, in series drawbacks such as occurrence of side-reactions (for example, combustion reaction of methacrolein), extremely low conversion and yield or very short active lifetime of the catalysts. On the other hand, the catalysts considered usable in the oxidation of methacrolein cannot be employed commercially in a longtime continuous operation since they give poor results or, even when good results are obtained in the early state of the reaction, they have a short active lifetime.

Usually, calcination treatment is performed in the preparation of oxidation reaction catalysts in order to increase the activity of the catalysts, finally stabilize the catalysts (i.e., prevent the reduction in yield and selectivity which may be caused by the change of the active state of the catalyst with the passage of the reaction time), and to prolong the active lifetime of the catalysts. However, the conventional catalysts have the following drawbacks in the calcination treatment:

i. If the calcination treatment is carried out at a temperature which is the same as or lower than the reaction temperature, the resulting catalyst may give some fair results in the early stage of the reaction but the results become increasingly poor with the passage of time. Thus, the catalyst has the defect of a short active lifetime.

ii. Conversely, if the calcination treatment is carried out at a temperature which is higher than the reaction temperature in an attempt to stabilize the catalyst and prolong its active lifetime, the reaction results become poor.

Under such circumstances, it has been considered very difficult to produce methacrylic acid commercially by the oxidation of methacrolein, in spite of the fact that the production of acrylic acid from acrolein has been carried out commerically. Accordingly, it has been concluded that the development of catalysts useful for the oxidation of methacrolein must be studied with different considerations than the catalysts used for the oxidation of acrolein.

Accordingly, it is an object of this invention to provide a new catalyst which can be used as an oxidation catalyst and which eliminates the defects of conventional oxidation catalysts for methacrolein, and which has excellent catalytic activity (namely, giving high yield and selectivity; e.g. of methacrylic acid) and a long active lifetime.

Another object of this invention is to provide a new catalyst which is effective not only for oxidation of methacrolein but also for oxidation of other unsaturated aldehydes such as acrolein.

[t has been found that these objects of the present invention can be achieved with an oxidation catalyst represented by the following empirical formula Mo P Q R O wherein Q is at least one element selected from the group consisting of Tl, Rb, Cs and K; R is at least one element selected from the group consisting of Cr, Si, Al, Ge and Ti; and a, b, c, d and e each represent the number of atoms of each element; the preferred atomic ratio of a:b:c;d is in the range of about 1: l0.0l- :l0.0l;20.0l; and e is the number of oxygen atoms determined by the valence requirements of the other elements present; a more preferred atomic ratio of a:b:c:d is in the range of about l:0.50.02:0.50.02- 21-002.

The catalysts according to the present invention can be used as an oxidation catalyst to produce unsaturated carboxylic acids in higher yields and selectivities than conventional catalysts used in the stable oxidation reaction of unsaturated aldehydes under feasible reaction conditions. Furthermore, the problem of the active lifetime of the catalyst has now been solved by the new catalyst used in this invention. Since the catalytic life can be maintained at a high level for prolonged periods of time, the reaction can be performed continuously over an extended period of time.

Generally, the conventional catalysts require delicate preparation conditions and operating procedures, thereby making it difficult to assure their reproducibility. However, the catalysts according to the present invention can be prepared by a simple procedure which always assures good activity of the catalyst and reproducible results.

The method of preparing the catalyst used does not affect the present invention as long as the ratio of atoms is within the above noted ranges. The catalyst may be made, for example, by the oxide mixing method, the evaporative drying method or the coprecipitation method, all of which are well known in the art. The starting constituent elements of the catalyst do not always have to be in the form of an oxide but may be in the form of a metal, metal salt, acid or base so long as they can be converted to the corresponding metal oxides by calcination. Typical examples include salts such as ammonium salts, nitrate of halides; free acids such as molybdic acid or phosphoric acid; isopolyacids such as pyrophosphoric acid, polyphosphoric acid or heptamolybdic acid; salts of isopolyacids such as an ammonium salt of an isopolyacid; heteropolyacids such as phosphomolybdic acid, silicomolybdic acid, aluminomolybdic acid, germanomolybdic acid, chromiummolybdic acid, titanomolybdic acid, phosphochromiummolybdic acid or phosphotitanomolybdic acid; or salts of heteropolyacids such as ammonium salt of a heteropolyacid. Prior to use, the catalyst composition is preferably calcined for several hours up to 15 or 16 hours at about 250-700C., preferably about 350-600C. in air, a reducing atmosphere or feed gas.

The catalyst can be prepared, for example, by mixing an aqueous solution containing a water-soluble compound of the R element with an aqueous solution containing ammonium molybdate, adding an aqueous solution containing phosphoric acid and an aqueous solution containing a nitrate of the element such as thallium nitrate, evaporatively drying the mixture while stirring, calcining the solid obtained, pulverizing the calcined product. and then molding it into pellets. Other examples of the catalyst preparation are described, for example, in the working examples to be given later. It is preferred that the catalyst be prepared so that the constituent elements will form complex compo s such as heteropolyacids, their acid salts or ammonium salts. Those skilled in the art can select the desired method of preparing the catalyst. It is not yet clear, however, in what state the individual elements of the catalyst composition, including oxygen, are in during the reaction when the catalyst is exhibiting its catalytic action.

While the catalyst can be used in the molded or powdered form, it is also possible to use it after dilution with an inert diluent. If desired, the catalyst can be de posited on a suitable inert carrier material. Examples of suitable carriers include alumina, silicon carbide, graphite, inert titania, zirconium oxide, thorium chloride, pumice, silica gel, or celite. The amount of the diluent or carrier is not critical since it has no substantial effect on the activity of the catalyst.

When the catalysts of the present invention are used to prepare an unsaturated carboxylic acid by reacting an unsaturated aldehyde with molecular oxygen at an elevated temperature in the vapor phase, the unsaturated aldehyde may preferably be acrolein or methacrolein. The source of molecular oxygen can be pure oxygen or air. Furthermore, it is possible to introduce into the reaction zone an inert diluent gas such as steam, nitrogen, argon, carbon dioxide, helium or a saturated hydrocarbon, for example, methane, ethane, propane or pentane.

The concentration of the unsaturated aldehyde in the feed gas to be introduced into the reactor is preferably from about I to about 25% by volume. On the other hand, the molar ratio of the starting unsaturated aldehyde to molecular oxygen is conveniently about l:(O.l-25.0), preferably about l:(0.0220.0). The reaction temperature is usually in the range of about 270 to 450C, preferably about 300 to about 420C, and the reaction pressure can be from a reduced pressure of less than atmospheric pressure to a superatmospheric pressure up to about l5 atms. Preferably, the reaction pressure is about l to about 5 atmospheres. The contact time (on the basis of 0C. and l atm.) is from about 0.01 to about 20 seconds, preferably about 0.l to about seconds. These conditions are suitability determined relative to each other in accordance with the catalyst employed and the reaction conditions. The type of reactor with which the catalysts of the present invention may be used may be any of those which are conventional, such as the fluidized, moving or fixed bed type, The reaction product can be recovered by known techniques; for example, condensation and liquefaction by means of a condenser or the extraction by water or a suitable solvent.

The invention is illustrated by the following Examples in which the catalysts are used in the conversion of unsaturated aldehydes, as indicated above. The conversion of the unsaturated aldehyde, the yield of the unsaturated carboxylic acid and the selectivity therefore are defined below. The analysis was carried out by gas chromatography in all cases.

unsaturated unreacted aldehyde unsaturated C fed (mol) aldeh de (mol) Onversmn i) unsaturated aldehyde fed (mol) unsaturated carboxylic acid formed (mol) Yield (7M X 100 unsaturated aldehyde fed (mol) Selectivity X 100 conversion EXAMPLE I 237 g of phosphomolybdic acid were dissolved in 300 ml. of water with heating, and an acqueous solution of 20 g of chromic anhydride dissolved in 100 ml. of water was added to the solution. The mixture was stirred, and an aqueous solution of 11.5 g of phosphoric acid in l00 ml. of water and an aqueous solution obtained by dissolving 53.2 g of thallium nitrate in 200 ml. of water with heating were further added. Then, ml. of 28% aqueous ammonia was added to this mixture, and the entire mixture was evaporated to dryness with stirring. The solid obtained was calcined at 400C. for 16 hours in a muffle furnace, pulverized, and molded into pellets each having a size of 5mm X 5 mm diameter. The atomic ratio of Mo:P:Tl:Cr of the resulting catalyst composition (Cat. No. 21-1) was l:O.l6:0.l6:0. 16. In the same way, Cat. No. a-2 and a-3 were prepared by changing the calcination temperature to 450 and 500C. respectively.

Similarly, Cat. No. a-4 to Cat. No. a-7 were prepared. Cat. No. a-6 was prepared by further adding ammonium molybdate in the preparation of Cat. No. a-l above.

Further, using rubidium nitrate, cesium nitrate and potassium nitrate instead of the thallium nitrate, Cat. No. 8 to Cat. No. 2l were prepared.

As comparisons, catalysts (Cat. No. X-l to X-9) were prepared at a calcination temperature of 450C. in the same way as mentioned above.

A stainless steel reaction tube 2.5 cm in inside diameter and 60 cm in length was packed with 100 ml. of the catalyst, and heated by a molten metal bath. A feed gas having a methacrolein: O :N :H O molar ratio of 1:l,5:l7.5:l0 was passed through the reaction tube while the contact time was adjusted to 3.6 seconds (on the basic of 0C., and 1 atm.). The results obtained are shown in Table I.

It is seen from the results shown in Table I that the catalysts of the present invention do not deteriorate even if the calcining temperature is high, and give markedly superior results at low reaction temperatures as compared with the comparison catalysts.

composition (Cat. No. b-l) obtained was 1:0.08:0.16:0.08. 1n the same way Cat. No. b-2 and Table 1 Run. Cat. CT RT MAL MAA No. No. Catalyst Composition (C) (C) conv. yield sel. 1 1

this invention 1-] a-l MQ R TL flr 400 345 80.3 58.6 73.0 -2 -2 450 343 80.7 60.0 74.4 -3 -3 500 355 79.3 60.1 75.8 -4 4 Mo,P ,,Tl,, Cr 450 350 79.3 59.1 74.5 -5 -5 MQ P TI CI 345 8 l .0 59.0 72.8 -6 -6 M0 Pq u5Tlo flCr 363 69.4 46.5 67.0 -7 -7 Mo P Tl cr 365 69.3 47.1 68.0 8 -15 Mo P Rb Cr 400 348 74.6 49.8 66.8 -9 -9 450 351 78.4 55.0 70.2 -10 -10 500 361 76.1 55.2 72.5 -1 1 -1 1 Mo P Rb Cr 450 350 76.5 54.3 71.0 -12 -12 Mo,P., Rb Cr 351 78.2 54.0 69.1 -13 -13 Mo,P Tl kb Cr 355 77.3 56.3 72.9 -14 -14 Mo.P,. ,,,Cs,. ,,Cr, 400 343 81.3 60.2 76.3 -15 -15 450 347 82.0 65.0 79.3 -16 -16 500 356 81.0 65.2 80.5 -17 -17 Mo,P Cs Cr,, 450 350 78.5 57.6 73 .4 I 8 l 8 I ILIE DJJII ILH r 357 76.9 57.0 74.2 -19 -19 Mo,P .;K Cr 400 345 74.0 50.4 68.] -20 -20 450 350 72.5 52.7 72.7 -Z1 -21 500 354 70.4 51.5 73.2

comparison [-22 x-l Mo,P Cr,, 450 382 46.7 20.3 43.5 -23 -2 Mo P Tl 385 49.4 30.6 61.9 -24 -3 Mo P kb 385 47.8 27.8 58.2 -25 -4 Mo P cs 375 50.5 30.4 60.2 -26 -5 Mo,P K 389 45.2 21.0 46.5 -27 6 MU TL CI 385 35.6 7.8 21.9 -28 -7 Mo Rb Cr 384 36.0 6.4 17.8 -29 -8 Mo,Cs., Cr., 383 37.5 9.5 25.3 -30 -9 Mo K cr 390 35.6 6.6 18.5

EXAMPLE 2 237 g of phosphomolybdic acid were dissolved in 400 ml. of water with heating, and an aqueous solution obtained by adding 17.0 g of silicon tetrachloride in 200 ml. of cold water dropwise was added to the solution. The mixture was heated, and further an aqueous solution obtained by dissolving 53.2 g of thallium nitrate in 200 m1. of water with heating was added. To the resulting mixture ml. of 28% aqueous ammonia were added, and the entire mixture was evaporated to dryness with stirring. The solid obtained was calcined at 400C. for 5 hours in a muffle furnace, pulverized, and molded into pellets each having a size of 5mm X 5mm diameter. The atomic ratio of Mo:P:Tl:Si of the catalyst Cat. No. b-3 were prepared by changing the calcination temperature to 450 and 500C. respectively.

Similarly, Cat. No. b-4 was prepared. Furthermore, Cat. No. b-5 to Cat. No. b-13 were prepared by using rubidium nitrate, cesium nitrate and p0- tassium nitrate instead of the thallium nitrate. Cat. No.

40 b-8 was prepared by further adding 1 1.5 g of phosphoric acid.

As comparisons, Cat. No. Y-l to Cat. No. Y-6 were prepared at the calcination temperature of 450C.

Using each of the catalyst compositions, methacrolein was oxidized under the same conditions as in Example 1. The results obtained are shown in Table 2.

Table 2 Run. Cat. CT RT MAL MAA No. No. Catalyst Composition (C) (C) conv. yield scl.

(this invention] 11-1 b-1 Mo,P., T1., Si 400 346 77.5 56.5 73.0 -2 -2 450 351 76.7 58.2 75.8 -3 -3 500 370 60.8 43.1 70.9 4 -4 MmR TI Si H 450 376 61.3 41.2 67.2 -5 -5 Mo P Rb si 400 348 75.0 52.5 70.0 -6 -6 450 352 77.3 56.3 72.8 -7 -7 500 374 61.2 40.2 65.7 -8 -11 Mo,P Rb Si 450 352 70.9 48.6 68.7 -9 -9 Mo P cs simm 400 347 79.3 57.0 71.) -10 -10 450 351 78.8 59.3 75.3 -11 -11 500 368 70.1 54.6 77.9 -12 -12 Mo P Rb Cs 450 362 71 0 49.1 69.3

(l.04 13 -13 Mo,P .K., ,;Si 450 360 62.3 43.6 70.0

[comparison] 11-14 Y-1 Mo l Si 450 383 42.4 16.3 38.4 -15 -2 Mo P Si 390 39.5 15.4 39.0 -16 -3 Mo Tl si 375 41.7 11.5 27.6 -17 -4 Mo Rb Si 380 40.1 10.1 25.9 -18 -5 MmCS Si 380 40.1 1 1.6 28.9 -19 -6 Mo,K., Si 391 38.5 7.0 18.2

EXAMPLE 3 l. 237 g of phosphomolybdic acid were dissolved in 300 ml. of water with heating, and an aqueous solution obtained by dissolving 75.0 g of aluminum nitrate in 200 ml. of water was added to the phosphomolybdic acid soiution. The mixture was stirred, and an aqueous solution of 34.5 g of 85% phosphoric acid in 150 ml. of water and an aqueous solution obtained by dissolving 53.2 g of thallium nitrate in 200 ml. of water were added to the mixture. Furthermore, 100 ml. of 28% aqueous ammonia were added, and the entire mixture was evaporated to dryness with stirring. The solid obtained was calcined at 450C. for 5 hours in a muffle furnace, pulverized, and molded into pellets each hav ing a size of 5 mm X 5 mm diameter. The atomic ratio of MozPzTlzAl in the catalyst composition obtained (Cat. No. c-l was 1:0.33:0. 16:0. 16. Similarly, Cat. No. c-Z to Cat. No. c-4 were prepared by using rubidium nitrate instead of the thallium nitrate.

As comparisons, Cat. No. 1-1 to Cat. No. Z 4 were prepared.

2. 2 [2 g of ammonium molybdate were dissolved in 400 ml. of water with heating. A suspension obtained by adding 21.4 g of germanium tetrachloride to 200 ml. of water was added. Further, an aqueous solution of l 1.5 g of 85% phosphoric acid in 100 ml. of water and an aqueous solution obtained by dissolving 53.2 g of thallium nitrate in 200 ml. of water with heating were added, and the entire mixture was evaporated to dryrubidium nitrate, cesium nitrate, and potassium nitrate instead of the thallium nitrate.

As comparisons, Cat. No. Z-6 to Cat. No. Z-l were prepared in the same way.

3. 57.0 g of titanium tetrachloride were hydrolyzed, and made alkaline with ammonia. The resulting precipitate was separated by filtration. The precipitate and 212 g of ammonium molybdate were dissolved in 500 m]. of water with heating. An aqueous solution of 69.0 g of 85% phosphoric acid in 200 m1 of water and an aqueous solution obtained by dissolving 79.8 g of thallium nitrate in 200 ml. of water with heating were added, and the entire mixture was evaporated to dryness with stirring. The solid obtained was calcined at 450C. for 16 hours in a muffle furnace. pulverized, and molded into pellets each having a size of mm X 5 mm diameter. The atomic ratio of MozPcTlzTi in the resulting catalyst composition (Cat. No. c-9) was l:0.5:0.25:0.25. Similarly, Cat. No. c-l0 to Cat. No. c-l2 were prepared by using rubidium nitrate, cesium nitrate and potassium nitrate instead of the thallium nitrate.

As comparisons, Cat. No. Z-ll to Cat. No. Z-l5 were prepared in the same way as above.

Using each of the catalyst compositions obtained in (1) to (3) above, methacrolein was oxidized in the same way as in Example 1. The results obtained are 30 given in Table 3.

Table 3 Run. Cat. CT RT MAL MAA No. No. Catalyst composition (C) (C) conv. Yield sel. (%1 (We) [this invention] lll l C-l Mo P Tl Ah 450 353 72.3 52.1 72.1 -2 2 M0 P Rb A1 360 68.9 42.5 61.7 3 3 M0 P CS -,A1 360 69.5 49.5 71.2 4 4 mom x m 362 5 8.7 40.1 68.3 -5 -5 M6.P., ,,,,T m 6. 363 69.6 49.3 70.8 -6 -6 M6,P,, .,,Rb., ,,o6. 365 67.2 47.0 69.9 7 -7 MO P CS ;GE 365 71.3 53.0 74. 3 -s a Mom K Ge 360 71.1 53.5 75.2 9 -9 M6.P,. .,Tl,, ,,Ti,,,, 364 68.2 47.1 69.1 -10 no Mo P Rb TL 367 66.5 43.6 65.6 '1 I -l l M0 P Cs Ti 360 68.9 47.0 68.2 -12 -12 M6,P,, ,K,, ,.,Ti., 370 56.9 38.5 67.7 13 -13 Mo.P K Rb Ge 363 65.2 44.1 67.7

[comparisonl 111-14 Z-l MO P A1 m 450 385 40.6 19.2 47.3 -15 -2 Mo Tl Al 380 36.7 8.2 22.3 46 -3 M6,R6.,,,Ai,, 384 35.0 8.0 22.9 -17 -4 M6,Cs,, ,,,m., 383 37.6 8.4 22.3 18 -5 Mt K Al 390 34.0 6.8 20.2 -l9 6 MO P GC 374 39.2 19.4 49.5 -20 -7 M6,T|., .,G,, 376 43.8 9.8 22.4 21 -8 Mo,Rb ,Gc 380 45.1 10.1 22.4 -22 -9 M6,Cs,, ,.,Gc..,,. 450 381 42.6 10.6 23.5 23 -10 M0,K Ge 384 42.8 11.0 25.7 -24 l l M0 E il 1 380 4] .6 25.2 60.6 -25 I2 M6,Ti., ,,Ti., 375 40.5 12.1 29.9 -26 3 M0 Rb Ti 383 42.0 12.0 28,6 27 -14 Mmcs ti 373 42.8 12.8 29.9 -28 l 5 M0,K ,Ti 389 40.1 9.8 24.4

ness with stirring. The solid obtained was calcined at EXAMPLE 4 450C. for 5 hours in a muffle furnace, pulverized, and molded into pellets each having a size of 5 mm X 5mm diameter. The atomic ratio of Mo:P:Tl:Ge in the catalyst composition obtained (Cat. No. c-S) was 1:0.08:0.l6:0.08. Furthermore, Cat. No. c-@ to Cat. No. c-S were prepared in the same way as above using Acrolein was oxidized under the same conditions as in Example 1 using each ofthe catalysts shown in Table 4 which were prepared in Examples 1, 2 and 3 at the calcination temperature of 450C. and adjusting the composition of the feed gas to acrolein: O :N :H O 1121829 (molar ratio). The results are shown in Table 4.

Table 4 Run Cat. RT Al AA No. No. Catalyst composition ("C) conv. yield scl.

lV-l a-2 Mo P Tl Cn 350 87.4 75.7 86.6 -2 6-2 MU P TL Si 355 88.3 75.2 85.2 -3 c-l MmP Tl AL 360 86.3 74.5 86.3 -4 c-5 Mo,P., T| Gc., 365 85.6 72.3 84.5 -5 -9 Mo p Tl Ti 366 82.7 71.0 85.9 -6 a 9 Mo,P Rb., C o,w 352 85.3 72.] 84.5 -7 6-6 Mo,P,, Rb ,.,Si 358 86.2 71.8 83.3 -8 c-Z Mo P Rb Al 36l 83.4 68.] 81.7 -9 c-6 MmP Rb GQ 364 86.1 70.8 82.2 -l0 c-lO MmP Rh T o 369 82.0 67.5 82.3 l l ml 5 MmP Cs Cr 350 90.3 82.0 90.8 l 2 6- I0 Mo,P., Cs Si 354 89.7 78.5 87.5 l 3 3 Mo,P,, Cs Al 362 86.] 73.6 85.5 l 4 c-7 Mo P,, Cs Ge., 362 87.7 77.4 88.3 I 5 c-l l Mo P Cs Ti 365 84.0 7L4 85.0 -l6 11-20 Mo P K Cr 357 85.6 71.3 83.3 l 7 bl 3 Mo P ,,,,K Si 365 78.9 63.7 80.7 l 8 C4 Mo P K Al 367 77.5 61.5 79.4 -19 c-8 Mo P K Ge 362 85.4 73.4 85.9 -20 c-l2 Mo P K Ti 373 80.0 60.3 75.4

EXAMPLE 5 Using each of the chosen catalysts, the longtime continuous reaction was performed in the same way. The performance of each of the comparison catalysts is shown 25 in Table 5. In the table, 0 under time elapsed" means the initial stage of the reaction.

lt is seen from Table 5 that the catalysts prepared according to the present invention do not lose their activity even after a lapse ofa long period of time, and prove to be excellent catalysts having a very long active life time. On the other hand, the activity of the comparison catalysts decreases abruptly within a short period of time, and therefore, they have a short active lifetime.

Table 5 Time MAL MAA Run Cat. CT elaps- RT conv. yield sel. No. No. Catalyst composition ("C) ed (C) (96) [this invention] V-l a-2 Mo P Tl cr 450 O 348 80.7 60.0 74.4 60 350 81.4 59.2 72.7 -2 b-2 Mo P ,Tl Si,, 450 0 351 76.7 58.2 75.8 60 353 78.] 57.1 73.l -3 c-l Mo P TL AL 450 0 353 72.3 52.l 72.1 60 358 7l.4 52.0 72.8 -4 c-5 Mo,P Tl Ge 450 0 363 69.5 49.6 71.4 60 367 67.8 48.3 71.2 -5 c-9 Mo,P Tl Ti 450 (1 364 68.3 47.6 69.7 60 368 69.0 47.0 68.l -6 M3 M0 .p ab cr 450 0 350 78.4 55.0 70.2 60 354 78.5 54.8 69.8 -7 b-6 Mo P,, Pb ;Si 450 0 352 77.3 56.3 72.8 60 355 76.2 55.l 72.3 -s C-2 M6,| ,.Rb,,,m,, 450 0 360 68.9 42.5 6 l .7 60 365 69.2 41.6 60.l -9 c-6 Mo P Rb Ge 450 0 365 67.2 47.0 69.9 60 369 65.8 46.] 70.5 -lU c-l0 Mo P Rb ,,Ti., 450 0 367 66.5 43.6 65.6 60 372 68.] 44.4 64.8 ll a-lS Mo P Cs cr 450 0 347 82.0 65.0 79.3 60 350 83.0 64.8 78.1 -l2 b-l0 M6,P.,,,,,cs., ,,si,, 450 0 78.8 59.3 75.3

354 78.5 58.8 74.9 l3 c-3 MO R CS AI 450 0 340 69.5 49.5 71.2 60 363 68.2 48.0 70.4 -14 6-7 Mo,P.,,.,,Cs., .,Ge 450 0 356 71.3 53.0 74.3 60 360 70.5 5|.7 73.3 '15 c] l Mo,P ,Cs -,Ti,, 450 0 360 68.9 47.0 68.2 60 364 69.| 45.9 66.4 -l6 a20 MmP K Cr 450 0 350 72.5 52.7 72.7 60 353 75.] 52.2 71.4 -17 b-I3 M6.P,, ,,,K.. ,,si., 450 0 360 62.3 43.6 70.0 60 366 60.2 41.8 69.4 l 8 c-4 Mo P K Al 450 0 362 58.7 40.l 68.3 60 368 57.2 38.7 67.7 [9 c-8 M6,P,, ..,.K,, ,,G@., 450 0 360 71.1 53.5 75.2 60 365 70.8 52.8 74.6 20 C-l2 mom x ri 450 0 370 56.9 38.5 67.7 60 375 55.7 37.l 66.6

Table 5 Continued Time MAL MAA Run Cat. CT elaps- RT conv. yield scl. No. No. Catalyst composition (Tl ed ("C) (70) (94 (days) [comparison] V-Zl x Mo P TL 400 345 58.5 40.4 (19.1 60 335 54.6 30.2 55.3

-22 2 MO P Rb 400 0 353 56.2 38.| 67.8 (i0 384 53.l 30.9 58.2

-23 -3 MU P Cs m 400 0 349 59.5 40.6 (18.2 60 396 55.3 28.7 51.9

24 -4 MU P K 400 U 355 50.4 30.| 59.7 60 39] 47.3 20.2 42.7

25 Mom a" 300 U 380 64.3 45.2 70.3 395 50.6 22.5 44.5

26 6 Mo P Si 350 U 360 63.0 35.3 56.0 398 58.2 21 .5 36.9

27 MO P AI 350 U 365 59.8 33.4 55.9 30 394 49.6 19.3 38.9

28 -8 Mo P Gc 400 O 335 62.1 45.0 72.4 60 390 47.5 25.4 53.5

29 -9 Mo P 511025 400 (J 355 64.5 58.8 60.2 60 385 50.2 26.3 52.4

wherein Q is at least one element selected from the group consisting of Tl, Rb, Cs and K; R is at least one element selected from the group consisting of Cr, Si, Al, Ge and Ti; and a, b, c, d and e each represent the number of atoms of each element; the atomic ratio of a:b:c:d is l:l0.0l:l0.0l:2-0.0l; and e is the number of oxygen atoms determined by the valence requirement of the other elements present.

2. The oxidation catalyst composition of claim 1, wherein the atomic ratio of a:b:c:d is l:0.5-0.02:0- .5-0.02:l-0.02.

3. The oxidation catalyst composition of claim 1, wherein the catalyst is diluted with an inert diluent.

4. The oxidation catalyst composition of claim 1,

wherein the catalyst is supported on an inert carrier. 

1. AN OXIDATION CATALYST COMPOSITION FOR USE IN THE VAPOR PHASE CATALYTIC OXIDATION OF UNSATURATED ALDEHYDES SELECTED FROM THE GROUP CONSISTING OF ACROLEIN AND METHACROLEIN TO A CORRESPONDING UNSATURATED CARBOXYLIC ACID WHICH CONSISTS ESSENTIALLY OF A CATALYTIC OXIDE OF MOLYBDENUM, PHOSPHORUS, AT LEAST ONE ELEMENT SELECTED FROM THE GROUP CONSISTING OF THALLIUM, RUBIDIUM, CESIUM, AND POTASSIUM, AND AT LEAST ONE ELEMENT SELECTED FROM THE GROUP CONSISTING OF CHROMIUM, SILICON, ALUMINUM, GERMANIUM AND TITANIUM, THE CATALYTIC OXIDE HAVING THE FOLLOWING FORMULA
 2. The oxidation catalyst composition of claim 1, wherein the atomic ratio of a:b:c:d is 1:0.5-0.02:0.5-0.02:1-0.02.
 3. The oxidation catalyst composition of claim 1, wherein the catalyst is diluted with an inert diluent.
 4. The oxidation catalyst composition of claim 1, wherein the catalyst is supported on an inert carrier. 